Profiled Sheeting Design Guide: Part 3 - Barbour Product Search

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Translucent sheets
Generally, rooflights formed of translucent sheeting, whether
site or factory assembled, are installed in the same manner as
fibre cement sheeting. The main difference is that translucent
material is thinner and therefore requires more frequent fixing.
Translucent sheet rooflights are laid unmitred, and since the
problem of compound layers at end lap situations does not
occur, adjacent fibre cement sheets are also left unmitred
at these junctions.
Single skin rooflights
Marley Eternit can supply a range of translucent
sheets to meet the requirements of ACR (M) 001:
2005 and with various fire ratings.
The translucent sheets should be supported at
each purlin position by profiled fillers, fibre cement
sheets, or fibre cement closure pieces (Fig.1).
End laps and side laps should be sealed with
10mm diameter extruded mastic sealant.
Self-sealing fasteners with a synthetic rubber shank
or seam bolts and washers with wide bearings are
recommended for side stitching. Self-tapping
screws and blind rivets should not be used for
stitching side laps.
Translucent sheets should be fixed through every
corrugation (not including the side laps) to the
purlins (Fig.2). The same fixings are used as for
fibre cement sheeting, but the holes for GRP
translucent sheets should be 2mm oversize, and
for polycarbonate sheets 6mm oversize (for sheet
lengths up to 2m, otherwise 9mm oversize).
All recommendations of the specialist translucent
sheeting supplier should be carefully observed.
The fixing recommendations will vary depending
on the type, grade and supplier of the material
being used.
Double skin rooflights
Double skin rooflights can be either Factory
Assembled Insulating Rooflights (FAIRs), or siteassembled.
For full details of Factory Assembled
Insulating Rooflights, consult the manufacturers.
Site-assembled rooflights
Site-assembled rooflights are more common
because they are more economical to install.
In double skin constructions, all four edges of a
translucent sheet or area should have rigid foam
supports/closures provided at the laps with the
fibre cement sheets. Support pieces should also
be installed where translucent sheets pass over
intermediate purlins.
Laylights
A double skinned flat box, made to the same
dimensions as the rigid insulation, can be obtained.
The joints between the double skinned box and the
insulation board are sealed with foil backed acrylic
adhesive tape 50mm wide to create a vapour proof
check within the building. Installation of the
weathering sheets above this, in effect, creates a
triple skin.
Factory Assembled Insulating Rooflights
(FAIRs) (Fig. 4)
FAIRs are delivered to site ready to install.
Packing may be needed at intermediate purlins,
if the air gap in the FAIR is not as deep as the
insulation. Always follow the manufacturer’s fixing
recommendations.
52 Profiled sheeting design guide